Lubricant



Fatented July 25, 1344 I uu 'rso s'rA'ras LUBRICANT Raphael Rosen,Elizabeth, N. 3., assignor to Standard Oil Development Company, acorporation of Delaware No Drawing. Application October 7, 1940,

Serial No. 360,127 I 16 Claims.

substituted -by various substituents, e. g., H,

N'Hz, halogen, N02 groups, Z represents a bivalent hydrocarbon radical,a bivalent sulfurcontaining hydrocarbon radical, e, g., -CH2Y, =CHSR, ora substituted derivative thereof, it

is a whole number, and X represents hydrogen,

a metal or other inorganic or organic cation, or hydrocarbon orsubstituted hydrocarbon radical, are incorporated in hydrocarbon oilswith advantageous results.

Some compounds of the above type have been incorporated, in the form ofvegetable oil blends thereof, into such products as paints, varnishes,and lacquers; however, the compounds which have been used for suchpurposes are generally insoluble in mineral oils. In order to impartsolubility in mineral oils to these compounds, it has" been foundadvantageous to include relatively long aliphatic chains in themolecules thereof; thus compounds suitable for use according to theprocess of this invention should contain at least 7 to 16 carbon atomsper'molecule. In addition to their solubility in mineral oils, thecompounds of this invention possess an added advantage from a physicalstandpoint; namely, they In other words, a sodium mercaptide is reactedwith a halogen-substituted organic acid to form a thioether derivativeof the organic acid. The mercaptides used may contain from 1 to 20 ormore carbon atoms per molecule, and the halogenated organic acids usedmay contain from 2 to 20 or more carbon atomsper molecule. As

indicated above, the mercap'tides and the halo-.

genated organic acids may contain aralkyl, cycloalkyl, aryl, alkarylgroups, or substituted derivatives thereof instead of, or in additionto, alkyl groups. The number of carbon atoms on each side of the sulfurgroup atom may be varied within awide range, and may be as low as 1carbon atom on either side. However, for the sakeof oil solubility, thetotal number of carbon atoms in the hydrocarbon groups on both sides ofthe sulfur group atom must beat least 6 in case both hydrocarbon groupsare aliphatic and at least about 15 in case one of the groups isaromatic. The aliphatic groups may be primary, secondary,

- or tertiary alkyl radicals. The cyclic groups may be aromatic orhydroaromatic radicals, or al- 5 kylated derivatives thereof. Themineral oil solubilityof the compounds of this invention, in

general, decreases in the following order: compounds containing onlyaliphatic groups, and having a total of more than 7 carbon atoms permolecule; compounds containingv alkylated hydroaromatic groups;compounds containing alkylated aromati groups: compounds containing aresuillcien'tly high in molecular weight so that they are non-volatile atautomotive engine temperatures thus, enabling them to stay with mineraloil and continually protect it from degradation.

It is not desired to limit the invention to any particular method ofpreparing these compounds. One method of preparing the acids isillustrated by the following reaction:

aromatic groups. In general, the compounds containing branched-chaingroups have lowerviscosities than do the corresponding straight-chaincompounds. A

Any of the halogens may be used in preparing 1 the halogenated acids,althoughchlorine is preferred since it is the cheapest. -When it isdesired that the final product should contain a halogen substituent, thehalogenated organic acid should contain twoor more halogen atoms permolecule.

other alkali metal mercaptides may. be used in pripiarlngthe compoundsof this invention, if desu Merely by way of illustration and not withthe intention of limiting the invention, the following Instead of thesodium mercaptides,

panflln wax. Cyclohexyl thioether oi chlorospecific examples orthioether derivatives of organic acids are enumerated:

Name Formula Phen l thioether oi capric acid But dphenyl thioether ofcaproic ac Chloaohexyl thioether oi caproic aci Butylphenyl thloether offatty ac ds derived (mm the oxidation of aflln wax.

Prop 1 t ioether of fatty acids der ved from the oxidation of 'CzH1S(CHI) .COOH

CsHuSQHCiCOOH ace cac -Tetramethylbutyl hydro: 011 phenylthicetheroiaceticaci ClHIQBCHsCOOH CioHnSCAHsCOOH CsH|CHiBCsH|COOH ClBllBCHlCOSBCuHuSCHaCSOH CHISCnHuCBSH CsHiiBCHlCOOH CuHuBCHsCOOH CHaSCnHuCOOHCHiBCI'IHaCOOH CeKnBCHrCOOH GallaSCsHaCOOH vCHI CaHrSHCl-IrC 01:!

CHI CtH'IBOHsBCOOH CaHrs (car's) ICHCOOH Bornyl' thioether of valericacid. Benz 1 thicether oi propionic ad Am (llthioether oi ethanethiolicLanai thioether oi ethanethlonic ac Methyl thioether oi octadecanethiom.iiolic acid. Amy l thioether of acetic acld. Lauryl thioether of aceticacid"- Methyl thioether oi sieario acld Methyl thioether of oleic acid..Secondary hexyl thioether of acetic acid 4 i-But l thioether oipropionic aci i-Propyl thioetber oi butyric acid.

l-Pro yl thioether of isobut c Ethyl thioether oi tri-tetra: methylenetri-thioethar of acetic acid. Di-finyl thlocthcr) oi isovaleric CB; 7

' (cimisiicncn-cmcooahibitors and sludge dispersers in mineral-oils suchas'motor lubricating oils, etc. Compounds of various metals, 'such asthe following, may be used in the reaction with the alkali metal saltsof the substitutedv organic acids: Ca, Ni, .Co, Pb, gn, Bi, Hg, Ba, Mg,Mn, etc. Specific compounds representative of'those which may be used aslubricating oil addition agents include the fol- [(cinnshcm m-cmcoolrs(Ce iiBCHClCOOhCo icimswmncoohsi (canascmcoobsa (cumiscmacoopco(CeHaBCuHuCOOhBi icmi smnuomcmcoo sn cmsqinncoopn lNmcm-winoscsnmoohm(cinuscaicoshm'n Express 1' The cobalt salt of alpha-amyl mercaptocaproic acid was prepared by the reaction of sodium alphaamyl 'mercaptocaproate with cobalt chloride in ethyl alcohol solution. The alcoholsolution of the cobalt alpha-amyl mercapto caproate is separated fromthe precipitated sodium chloride by filtration, and then evaporated todryness. The resulting material was shown to .be non-corrosive tobearing metals, and to be efiectlve as an oxidation inhibitor forlubricating oils. 1

A further important property of lubricating oil addition agents is theirability todisperse sludge formed in the oil during the operation of theengine in which the oil is being used. Ii. this sludge is not kept indispersed form, it settles out on the cylinder walls and pistonsurfaces,

and, ii this is allowed to go on for a time, the pistons become stuckand incapable of further movement until the sludge deposits (convertedto hard carbon and varnish by the heat or the engine) are removed.

A laboratory test has been-developed for determinlng the sludgedispersing properties of oils. According to the test procedure, 450 g.of oil are heated to 225 F. and agitated during the gradual addition of30 g. of carbon black. Alter 30 minutes of further stirring, thesuspension is transferred to a graduated 500 cc. cylinder, allowed tosettle for .22, hours in an oil bath maintained at 200 F., and thenallowed to stand for an additional two hours at room temperature. Whenthe oil contains no dispersing agent, the carbon black settles out andleaves a clear, supernatant layer of oil. In the presence of aneffective dispersing agent, however, the carbon black remains sus--pended throughout the entire volume of oil in the cylinder. The amountof carbon black suspended in the zone approximately 25 cc. below thesurface of the oil is determined by a turbidimetric comparison method,and reported in mgs. of carbon per cc. of oil. The cobalt salt oralpha-amyl mercapto caproic acid was tested by this method,

'and the sludge dispersion results are given below:

Sludge dispersion results Oil a Ce. 0! 01 clear oil 0n.u o in Oil A+:=5%additive 7 o a lnaphthenic base lube oil having a Baybolt ma oi as see.a r

Thus, it may readily be seen that this addition agent, cobalt alpha-amylmercapto caproate, is eflective as asludge dispersing agent. 7

Exam 2 assasso I leum phenolates, which are included for purposesofcomparison: I

S. 0. D. corrosion results: loss in bearing on Bearing weight. nns.

metals 1 hr. i hrs 5 hrs.

Oil A+0.25% i Al-Ca (d-Ag. 0.020 0.11" 0.294 sweater oil soaps. u-Pb 0.032 0 077 0.147 Oil A+0.5% of Ca petroleum i Cd-Ag. 0.320 phenolates(u-Pb. ,i. 0.082 Oil A+0.25% of Ca q-Inuryl {("d-Ag 0.000 0.03; 0.089mercapto caproate v (in-Pb" 0.009 0.042 0.084 Oil A+0.5% of Ca mlaury]{Pd-Ac 0.002 0.052 0.115 mercapto caproatc. (u-Pb. 0.006 0 037' 0.083

1 A naphthenic hase lube oil having a Sayholt viscosity oi 55'scc. at210 F.

It will be seen from these data that the addition agent of thisinvention protects bearings from corrosion better (with one exception)than do the other products listed above. In the cases of the calciumpetroleum phenolates and the calcium a-lauryl mercapto caproate, thecopper-lead bearings were corroded to the same extent after five hours,but the cadmium-silver bearings were protected from corrosion muchbetter by the product of this invention.

Thus, the metal soaps of thioether derivatives of organic acids areeminently suitable for use as lubricating oil addition agents, in thatthey are .eifective sludge dispersers and oxidation inhibitors, and arenon-corrosive to certain bearing metals and other engine parts.

Metallic salts of substituted organic acids containing selenium ortellurium atoms instead of sulfur atoms may also be used as lubricatingoil addition agents.

The metal soaps of thioether derivatives of organic acids also mayadvantageously be incorporated in grease and extreme pressure lubricantcompositions; the following formulae are two examples of suitablecompositions:

Cobalt, manganese, and lead soaps of thioether derivatives of organicacids have good drying properties and may be used to accelerate thefilm-forming and hardening of vegetable or other fatty oils, such aslinseed oil. For example, it has been found that lead alpha-amylmercapto stearate, [Ciel-I33 C5H11S) CHCOOhPb, increases the oxygenabsorption rateof linseed oil (measured by the pressure decrease, inmillimeters of .purpose than is the lead soap.

in addition to the thioether derivatives of organic acids and theirmetal soaps, inorganic (other than metal) and organic soaps and estersof these acids have also been found to be useful as lubricating oiladdition agents. The inorganic and organic soaps may be prepared byneutralizing the acids with the appropriate bases, such as amines,phosphines, and ammonium hydroxide. .Esters of the thioether derivativesof organic acids may readily be prepared by reacting the acid with anorganic compound containing a free hydroxyl or mercapto group in thepresence of a small quantity of a catalyst, such as a mineral acid. Theresultingesters may also contain free hydroxyl or mercapto groups, sothat metallic derivatives thereof can be prepared and used aslubricating oil addition agents. Several examples of such thioetherderivatives of organic acids which are suitable for use as lubricantadditives are given below: Ammonium octadecyl mercapto caproateCusI-IsvSCsHwCOONHk Arnyl tetramethylbutyl cyclohexyl acetateCsHnCsHxoSCI-ICOOQsHu 'mercapto Cobalt salt of the lauryi ester of thetetramethyl- CsHnCcHa S Cal-14C S 0 C1zHz5 CaHnCiHaS CiHiC S O CuHzsAlso, if, desired. thioether derivatives of naphthenic acids can beused, particularly of the naphthenic acids obtainable from petroleumfractions. It is not intended that this invention be lim-' ited to" amof the specific examples given nor to any theories suggested as to theoperation of the invention, but, in the appended claims, it is intendedto claim all novelty inherent in the invention as broadly as the priorart permits.

' I claim: l. A lubricant comprising a major portion of a minerallubricating oil and a small amount of a compound having the generalformula where R is an aliphatic hydrocarbon radical and Z represents ahydrocarbon radical selected from the class con'sisting of aliphatic andnaphthenic radicals, both R and Z being linked to the sulfur atom bycarbon bonds and having a total of more than 6 carbon atoms, Y isanelement of the group comprising oxygen and sulfur, and X is asubstituent which by hydrolysis of the compound is replaced by hydrogen.

2. A lubricant comprising a major portion of a mineral lubricating oiland a small amount of a compound having the general formula 'where R andZ represent aliphatic hydrocarbon radicals linked to the sulfur atom bycarbon bonds and having a total of more than 6 carbon atoms, and X is asubstituent which by hydrolysis of the compound is replaced by hydrogen.

4. A lubricant comprising a major portion of a mineral lubricating oiland a small amount a salt having the general formula whereR and Z arealiphatic hydrocarbon radicals linked to the sulfur atom by carbonbondsand having a total of more than 6 carbon atoms, Y is an. element ofthe group comprising oxygen and sulfur, X is an inorganic cation, m isan integer corresponding to the valence oi X.

5. A lubricant comprising a major portion of a mineral lubricating oiland a small amount of a salt having the general-formula where R and Zare aliphatic hydrocarbon radibon atoms.

at least one of the groups R and Z contains at cals linked to the sulfuratom by carbon bonds and having a total of more than 6 carbon atoms, Yis an-element of the group comprising oxygen and sulfur, X is an organiccation, 1n is an integer corresponding to the valence of X.

6, A lubricant comprising a major proportion of a mineral lubricatingoil and a small amount of an oil-soluble organic compound having thegeneral formula RYZCOOM, in which Y is selected from the groupconsisting of sulfur, selenium and tellurium, R and Z representhydrocarbon radicals containing a total of more than six saturatedaliphatic carbon atoms, each of said radicals having a carbon atomattached to Y, and M is a metal.

7. A lubricant comprising a major proportion of a mineral lubricatingoil and a small amount of an oil-soluble organic compoundv having thegeneral formula (RSZCOOMM, in which R and Z are both hydrocarbonradicals containing allphatic groups, said hydrocarbon radicalscontaining a total of more than six saturated aliphatic carbon atoms, Mis a metal seelcted from groups I! to V of the periodic table, and m isan integer corresponding to the valence of M.

8. A lubricant according to claim 1 in which the group is a naphthenicacid group.

9. A lubricant according to claim 2 in which Z represents the hydrcarbonradicals present. in

fatty acids obtained by the oxidation of paramn waxes,

10. A lubricant according to claim 2 in which R is an alkyl group havingmore than ten car- 11. A lubricant according to claim 2 in which leastone substituent halogen atom.

12. A lubricant according to claim 4 in which X is a polyvalentmetalselected from groups II,'

III, IV, V, VII, and VIII of the periodic .table. 13. A lubricantaccording to claim 4 in which X is a bivalent metal.

of mineral lubricating oil and a small amount of lead alpha-(amylmercapto) stearate.

15. A lubricant comprising a major porportion of a mineral lubricatingoil and a small amount ofcobalt amyl mercapto caproate. r

16. A lubricant comprising a major proportion of a mineral lubricatingoil and a small amount caproate.

of calcium lauryl mercapto RAPHAEL ROSE'N.

14. A lubricant comprising a major proportion I

